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Subject[RFC 23/26] union-mount: copyup on rename
Add copyup renaming of regular files on union mounts. Directories are still
lazyly copied with the help of user-space.

Signed-off-by: Jan Blunck <jblunck@suse.de>
---
fs/namei.c | 133 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
fs/union.c | 8 ++-
2 files changed, 129 insertions(+), 12 deletions(-)

--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1491,6 +1491,8 @@ static int fastcall do_path_lookup(int d
nd->mnt = mntget(fs->pwdmnt);
nd->dentry = dget(fs->pwd);
read_unlock(&fs->lock);
+ /* Force a union_relookup() */
+ nd->um_flags = LAST_LOWLEVEL;
} else {
struct dentry *dentry;

@@ -3478,6 +3480,97 @@ int vfs_rename(struct inode *old_dir, st
return error;
}

+int vfs_rename_union(struct nameidata *oldnd, struct path *old,
+ struct nameidata *newnd, struct path *new)
+{
+ struct inode *old_dir = oldnd->dentry->d_inode;
+ struct inode *new_dir = newnd->dentry->d_inode;
+ struct qstr old_name;
+ char *name;
+ struct dentry *dentry;
+ int error;
+
+ if (old->dentry->d_inode == new->dentry->d_inode)
+ return 0;
+
+ error = may_whiteout(old->dentry, 0);
+ if (error)
+ return error;
+ if (!old_dir->i_op || !old_dir->i_op->whiteout)
+ return -EPERM;
+
+ if (!new->dentry->d_inode)
+ error = may_create(new_dir, new->dentry, NULL);
+ else
+ error = may_delete(new_dir, new->dentry, 0);
+ if (error)
+ return error;
+
+ DQUOT_INIT(old_dir);
+ DQUOT_INIT(new_dir);
+
+ error = security_inode_rename(old_dir, old->dentry,
+ new_dir, new->dentry);
+ if (error)
+ return error;
+
+ error = -EBUSY;
+ if (d_mountpoint(old->dentry) || d_mountpoint(new->dentry))
+ return error;
+
+ error = -ENOMEM;
+ name = kmalloc(old->dentry->d_name.len, GFP_KERNEL);
+ if (!name)
+ return error;
+ strncpy(name, old->dentry->d_name.name, old->dentry->d_name.len);
+ name[old->dentry->d_name.len] = 0;
+ old_name.len = old->dentry->d_name.len;
+ old_name.hash = old->dentry->d_name.hash;
+ old_name.name = name;
+
+ /* possibly delete the existing new file */
+ if ((newnd->dentry == new->dentry->d_parent) && new->dentry->d_inode) {
+ /* FIXME: inode may be truncated while we hold a lock */
+ error = vfs_unlink(new_dir, new->dentry);
+ if (error)
+ goto freename;
+
+ dentry = __lookup_hash_kern(&new->dentry->d_name,
+ newnd->dentry, newnd);
+ if (IS_ERR(dentry))
+ goto freename;
+
+ dput(new->dentry);
+ new->dentry = dentry;
+ }
+
+ /* copyup to the new file */
+ error = __union_copyup(old, newnd, new);
+ if (error)
+ goto freename;
+
+ /* whiteout the old file */
+ dentry = __lookup_hash_kern(&old_name, oldnd->dentry, oldnd);
+ error = PTR_ERR(dentry);
+ if (IS_ERR(dentry))
+ goto freename;
+ error = vfs_whiteout(old_dir, dentry);
+ dput(dentry);
+
+ /* FIXME: This is acutally unlink() && create() ... */
+/*
+ if (!error) {
+ const char *new_name = old_dentry->d_name.name;
+ fsnotify_move(old_dir, new_dir, old_name.name, new_name, 0,
+ new_dentry->d_inode, old_dentry->d_inode);
+ }
+*/
+freename:
+ kfree(old_name.name);
+ return error;
+}
+
+
static int do_rename(int olddfd, const char *oldname,
int newdfd, const char *newname)
{
@@ -3495,10 +3588,7 @@ static int do_rename(int olddfd, const c
if (error)
goto exit1;

- error = -EXDEV;
- if (oldnd.mnt != newnd.mnt)
- goto exit2;
-
+lock:
old_dir = oldnd.dentry;
error = -EBUSY;
if (oldnd.last_type != LAST_NORM)
@@ -3536,15 +3626,40 @@ static int do_rename(int olddfd, const c
error = -ENOTEMPTY;
if (new.dentry == trap)
goto exit5;
- /* renaming on unions is done by the user-space */
+ /* renaming of directories on unions is done by the user-space */
error = -EXDEV;
- if (is_unionized(oldnd.dentry, oldnd.mnt))
+ if (is_unionized(oldnd.dentry, oldnd.mnt) &&
+ S_ISDIR(old.dentry->d_inode->i_mode))
goto exit5;
- if (is_unionized(newnd.dentry, newnd.mnt))
+ /* renameing of other files on unions is done by copyup */
+ if ((is_unionized(oldnd.dentry, oldnd.mnt) &&
+ (oldnd.um_flags & LAST_LOWLEVEL)) ||
+ (is_unionized(newnd.dentry, newnd.mnt) &&
+ (newnd.um_flags & LAST_LOWLEVEL))) {
+ dput_path(&new, &newnd);
+ dput_path(&old, &oldnd);
+ unlock_rename(new_dir, old_dir);
+ error = union_relookup_topmost(&oldnd,
+ oldnd.flags & ~LOOKUP_PARENT);
+ if (error)
+ goto exit2;
+ error = union_relookup_topmost(&newnd,
+ newnd.flags & ~LOOKUP_PARENT);
+ if (error)
+ goto exit2;
+ goto lock;
+ }
+
+ error = -EXDEV;
+ if (oldnd.mnt != newnd.mnt)
goto exit5;

- error = vfs_rename(old_dir->d_inode, old.dentry,
- new_dir->d_inode, new.dentry);
+ if (is_unionized(oldnd.dentry, oldnd.mnt) &&
+ (old.dentry->d_parent != oldnd.dentry))
+ error = vfs_rename_union(&oldnd, &old, &newnd, &new);
+ else
+ error = vfs_rename(old_dir->d_inode, old.dentry,
+ new_dir->d_inode, new.dentry);
exit5:
dput_path(&new, &newnd);
exit4:
--- a/fs/union.c
+++ b/fs/union.c
@@ -1030,9 +1030,11 @@ int __union_copyup(struct path *old, str
goto out;
}

- dput_path(new, new_nd);
- new->dentry = dentry;
- new->mnt = new_nd->mnt;
+ if (new->dentry != dentry) {
+ dput_path(new, new_nd);
+ new->dentry = dentry;
+ new->mnt = new_nd->mnt;
+ }
out:
if (new->dentry != dentry)
dput(dentry);
--

-
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